What did you call your grandparents?
What do your children call their grandparents, or great-grandparents?
Some families use ethnic words for grandma and grandpa. Some go with "Grandma Brown" or "Grandpa Joe." Some choose completely personal nicknames, especially when there are multiple grandmas or grandpas around. Some of the nicknames come out of children's mispronunciations; my FarAwaySis could only manage "Bamma" and "Bampa" as a toddler.
My own children called my mother "Grandma Soup." The only reason for that--besides distinguishing her from their other grandmother--was that when The Apprentice was very small, my mother used to come babysit her sometimes, and stay for lunch, and lunch was usually...soup. So--Grandma-who-comes-for-soup, Grandma Soup.
Here's a list of all kinds of other possibilities.